U.S. patent application number 17/501946 was filed with the patent office on 2022-04-21 for systems, methods, and devices for creating a custom output spectral power distribution.
The applicant listed for this patent is Electronic Theatre Controls, Inc.. Invention is credited to Gary Bewick, William R. Florac, Evan Gnam, Wendy Luedtke, Michael Wood.
Application Number | 20220124884 17/501946 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220124884 |
Kind Code |
A1 |
Florac; William R. ; et
al. |
April 21, 2022 |
SYSTEMS, METHODS, AND DEVICES FOR CREATING A CUSTOM OUTPUT SPECTRAL
POWER DISTRIBUTION
Abstract
Systems, methods, and devices described herein provide for
operating a lighting fixture with a plurality of light sources at a
target chromaticity with a target output spectral power
distribution. The methods include multiplying a first spectral
power distribution by a second spectral power distribution to
determine a product spectral power distribution, multiplying the
product spectral power distribution by an illuminant spectral power
distribution to determine the target output spectral power
distribution at the target chromaticity, and driving the plurality
of light sources at intensities corresponding to the target output
spectral power distribution.
Inventors: |
Florac; William R.; (Verona,
WI) ; Gnam; Evan; (Middleton, WI) ; Luedtke;
Wendy; (Brooklyn, NY) ; Bewick; Gary; (Cross
Plains, WI) ; Wood; Michael; (Austin, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Electronic Theatre Controls, Inc. |
Middleton |
WI |
US |
|
|
Appl. No.: |
17/501946 |
Filed: |
October 14, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63093952 |
Oct 20, 2020 |
|
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International
Class: |
H05B 45/20 20060101
H05B045/20; H05B 45/3577 20060101 H05B045/3577 |
Claims
1. A method for operating a lighting fixture with a plurality of
light sources at a target chromaticity with a target output
spectral power distribution, the method comprising: determining a
first distance between the target chromaticity and a first
chromaticity with a first spectral power distribution; determining
a second distance between the target chromaticity and a second
chromaticity with a second spectral power distribution; scaling the
first spectral power distribution by a first scaling factor to
arrive at a first scaled spectral power distribution, the first
scaling factor is based on the first distance; scaling the second
spectral power distribution by a second scaling factor to arrive at
a second scaled spectral power distribution, the second scaling
factor is based on the second distance; adding the first scaled
spectral power distribution and the second scaled spectral power
distribution to arrive at the target output spectral power
distribution at the target chromaticity; and driving the plurality
of light sources at intensities corresponding to the target output
spectral power distribution.
2. The method of claim 1, wherein the first distance is measured
between MacAdam-ellipses corresponding to the target chromaticity
and the first chromaticity in the CIE 1931 x-y color space.
3. The method of claim 1, wherein the first distance is the
Euclidean distance between the target chromaticity and the first
chromaticity in the CIE 1960 u-v color space.
4. The method of claim 1, wherein the first distance is the
.DELTA.E between the target chromaticity and the first chromaticity
in the CIE L*a*b* color space.
5. The method of claim 1, wherein the first distance is a sum of an
absolute difference of cartesian coordinates of the target
chromaticity and the first chromaticity.
6. The method of claim 1, wherein the first scaling factor is based
on a user preference.
7. The method of claim 6, wherein the user preference is an amount
of a waveband in the output spectral power distribution.
8. The method of claim 1, wherein the first scaling factor is based
on a weighting function.
9. The method of claim 8, wherein the weighting function is a
polynomial function.
10. The method of claim 8, wherein the weighting function is an
exponential or logarithmic function.
11. The method of claim 1, wherein the first chromaticity with the
first spectral power distribution corresponds to a chromaticity and
a spectral power distribution resulting from the use of a filter in
front of an illuminant.
12. The method of claim 1, wherein the first chromaticity with the
first spectral power distribution corresponds to a chromaticity and
spectral power distribution of a tungsten lamp.
13. The method of claim 1, wherein the first chromaticity with the
first spectral power distribution corresponds to a user-created
spectral power distribution.
14. The method of claim 1, wherein the first chromaticity with the
first spectral power distribution corresponds to a physical
emission spectrum.
15. A method for operating a lighting fixture with a plurality of
light sources at a target chromaticity with a target output
spectral power distribution, the method comprising: multiplying a
first spectral power distribution by a second spectral power
distribution to determine a product spectral power distribution;
multiplying the product spectral power distribution by an
illuminant spectral power distribution to determine the target
output spectral power distribution at the target chromaticity; and
driving the plurality of light sources at intensities corresponding
to the target output spectral power distribution.
16. The method of claim 15, wherein the product spectral power
distribution corresponds to the spectral power distribution
resulting from a combination of at least two filters in front of an
illuminant.
17. The method of claim 15, wherein the illuminant spectral power
distribution corresponds to the spectral power distribution of a
tungsten lamp.
18. A method for operating a lighting fixture with a plurality of
light sources at a target chromaticity with a target output
spectral power distribution, the method comprising: exponentiating
a first spectral power distribution by an exponent to determine an
exponential spectral power distribution; multiplying the
exponential spectral power distribution by an illuminant spectral
power distribution to determine the target output spectral power
distribution at the target chromaticity; and driving the plurality
of light sources at intensities corresponding to the target output
spectral power distribution.
19. The method of claim 18, wherein the exponent corresponds to a
user-selected opacity.
20. The method of claim 19, wherein the user-selected opacity is a
negative value.
21. The method of claim 18, wherein the illuminant spectral power
distribution corresponds to the spectral power distribution of a
tungsten lamp.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 63/093,952, filed Oct. 20, 2020, the entire
content of which is hereby incorporated by reference.
FIELD
[0002] Embodiments described herein relate to controlling the
spectral content of an output of a lighting fixture.
SUMMARY
[0003] Luminaires or lighting fixtures are capable of producing a
wide gamut of colors by combining light from a plurality of light
sources. A common way of visualizing the color gamut of a lighting
fixture is using the International Commission on Illumination
("CIE") 1931 color space chromaticity diagram. The CIE 1931 color
space chromaticity diagram is a two-dimensional representation of
the colors in the visible spectrum in which each color is
identified by an x-y coordinate (i.e., [x, y]). While the
chromaticity of a color can be defined in terms of an x-y
coordinate, a Y tristimulus value is used as a measure of
brightness or luminance resulting in the CIE xyY color space.
[0004] The use of x-y coordinates (or other conventional metrics
for relaying color information such as hue-saturation-intensity
["HSI"], red-green-blue ["RGB"], etc.) to identify colors provides
a consistent technique for selecting the color outputs of
luminaires or lighting fixtures. However, they do not necessarily
translate to a consistent output spectrum across different lighting
fixtures in that the same color can be produced by many different
spectra. As such, the user is unable to precisely control the
spectral content of an output of a lighting fixture using color
coordinates.
[0005] Methods for driving light sources to achieve a target color
as an output of a lighting fixture, as well as manually controlling
the spectral content of the output of the lighting fixture, are
disclosed in, for example, U.S. Pat. No. 8,723,450, the entire
content of which is incorporated herein by reference. A color
control methodology (e.g., HSI, RGB, etc.) is used to produce the
target or desired color output from the lighting fixture, and then
a user is able to manually control the spectral content of the
output of the lighting fixture by increasing or decreasing the
output intensity value of one or more of the light sources. Based
on the user's desired change in the spectral content of the output
of the lighting fixture, a new set of light source output intensity
values to maintain the target color are determined and used to
operate the lighting fixture.
[0006] However, conventional control of a lighting fixture output
spectral content requires the user to manually and individually
increase or decrease an output intensity value of one or more of
the light sources. An unfamiliar user may not understand what
spectral content to adjust in the lighting fixture in order to
achieve a desired effect. For example, lighting designers are
familiar with using conventional filters (e.g., color filters, gel
filters, glass dichroic filters, etc.) to create an output color
with a specific spectral power distribution from a specific light
source, but would not know how to create a new color with a
spectral power distribution similar to that of the conventional
filter from a different light source.
[0007] Conventional filters are mounted at the lighting fixture's
output end and absorb or reflect some wavelengths of light while
transmitting other wavelengths of the light emitted by an
illuminant (e.g., an incandescent lamp). The light passing through
the filter provides an output light beam from the lighting fixture
with a specific spectral composition. Several hundred different
colors can be provided by use of such filters, and certain filter
colors have been widely accepted as standard colors in the
industry. However, the use of such physical filters is inefficient
since the process of filtering out wavelengths is subtractive, and
absorption of non-selected wavelengths generates heat as lost
energy. The replacement of incandescent lamps and gas-discharge
lamps with light emitting diodes (LEDs) provided an alternative to
color filters because a desired color can instead be produced by
providing electrical power in selected amounts to differently
colored LEDs in the lighting fixture, with the final color produced
by additive mixing of these. Methods for matching an LED fixture
output to a reference filter color is disclosed, for example, in
U.S. Pat. No. 6,683,423, the entire content of which is
incorporated herein by reference.
[0008] Users also often prefer to work with filters of a given
manufacturer (e.g., within a filter family). While sometimes this
is out of convenience or custom, there may also be a spectral
purpose. For example, a particular "filter family" may have certain
desirable spectral similarities whether by design or by the nature
of its manufacturing method. Even in cases where multiple
manufacturers offer filters that would produce nominally identical
chromaticities, the spectrums used to achieve those chromaticities
may vary widely.
[0009] In addition, conventional control techniques provide no
ability to operate a lighting fixture output at a desired color
with a spectral content (i.e., a spectral power distribution)
similar to that of other known spectral power distributions. For
example, a lighting designer may be familiar with an industry
standard green filter that produces a green color with a specific
spectral power distribution. The lighting designer may want to
select another green variant color (e.g., a lime-green) while
maintaining as many of the similarities to the well-known green
filter. This new color (lime-green) can be produced by the lighting
fixture with several different spectral power distributions (i.e.,
metamer control), but the lighting designer has no understanding as
to how to create the new color while maintaining characteristics
from a known spectral power distribution. Specifically, one
characteristic the lighting designer may want to recreate from a
known filter is a color's "feel" or how the lighting fixture light
output on an object appears to an observer. The "feel" or observer
perception of an object illuminated by a lighting fixture output is
determined, at least in part, by the spectral power distribution of
the lighting fixture light output.
[0010] Methods described herein provide for operating a lighting
fixture with a plurality of light sources at a target chromaticity
with a target output spectral power distribution. The methods
include determining a first distance between the target
chromaticity and a first chromaticity with a first spectral power
distribution, determining a second distance between the target
chromaticity and a second chromaticity with a second spectral power
distribution, and scaling the first spectral power distribution by
a first scaling factor to arrive at a first scaled spectral power
distribution. The first scaling factor is based on the first
distance. The methods also include scaling the second spectral
power distribution by a second scaling factor to arrive at a second
scaled spectral power distribution. The second scaling factor is
based on the second distance. The methods also include adding the
first scaled spectral power distribution and the second scaled
spectral power distribution to arrive at the target output spectral
power distribution at the target chromaticity, and driving the
plurality of light sources at intensities corresponding to the
target output spectral power distribution.
[0011] In some aspects, the first distance is measured between
MacAdam-ellipses corresponding to the target chromaticity and the
first chromaticity in the CIE 1931 x-y color space.
[0012] In some aspects, the first distance is the Euclidean
distance between the target chromaticity and the first chromaticity
in the CIE 1960 u-v color space.
[0013] In some aspects, the first distance is the .DELTA.E between
the target chromaticity and the first chromaticity in the CIE
L*a*b* color space.
[0014] In some aspects, the first distance is the sum of the
absolute difference of the cartesian coordinates of the target
chromaticity and the first chromaticity.
[0015] In some aspects, the first scaling factor is based on a user
preference.
[0016] In some aspects, the user preference is an amount of a
waveband in the output spectral power distribution.
[0017] In some aspects, the first scaling factor is based on a
weighting function.
[0018] In some aspects, the weighting function is a polynomial
function.
[0019] In some aspects, the weighting function is an exponential or
logarithmic function.
[0020] In some aspects, the first chromaticity with the first
spectral power distribution corresponds to the chromaticity and
spectral power distribution resulting from the use of a filter in
front of an illuminant.
[0021] In some aspects, the first chromaticity with the first
spectral power distribution corresponds to the chromaticity and
spectral power distribution of a tungsten lamp.
[0022] In some aspects, the first chromaticity with the first
spectral power distribution corresponds to a user-created spectral
power distribution.
[0023] In some aspects, the first chromaticity with the first
spectral power distribution corresponds to a physical emission
spectrum.
[0024] Methods described herein provide for operating a lighting
fixture with a plurality of light sources at a target chromaticity
with a target output spectral power distribution. The methods
include multiplying a first spectral power distribution by a second
spectral power distribution to determine a product spectral power
distribution, multiplying the product spectral power distribution
by an illuminant spectral power distribution to determine the
target output spectral power distribution at the target
chromaticity, and driving the plurality of light sources at
intensities corresponding to the target output spectral power
distribution.
[0025] In some aspects, the product spectral power distribution
corresponds to the spectral power distribution resulting from a
combination of at least two filters in front of an illuminant.
[0026] In some aspects, the illuminant spectral power distribution
corresponds to the spectral power distribution of a tungsten
lamp.
[0027] Methods described herein provide for operating a lighting
fixture with a plurality of light sources at a target chromaticity
with a target output spectral power distribution. The methods
include exponentiating a first spectral power distribution by an
exponent to determine an exponential spectral power distribution,
multiplying the exponential spectral power distribution by an
illuminant spectral power distribution to determine the target
output spectral power distribution at the target chromaticity, and
driving the plurality of light sources at intensities corresponding
to the target output spectral power distribution.
[0028] In some aspects, the exponent corresponds to a user-selected
opacity.
[0029] In some aspects, the user-selected opacity is a negative
value.
[0030] In some aspects, the illuminant spectral power distribution
corresponds to the spectral power distribution of a tungsten
lamp.
[0031] Before any embodiments are explained in detail, it is to be
understood that the embodiments are not limited in its application
to the details of the configuration and arrangement of components
set forth in the following description or illustrated in the
accompanying drawings. The embodiments are capable of being
practiced or of being carried out in various ways. Also, it is to
be understood that the phraseology and terminology used herein are
for the purpose of description and should not be regarded as
limiting. The use of "including," "comprising," or "having" and
variations thereof are meant to encompass the items listed
thereafter and equivalents thereof as well as additional items.
Unless specified or limited otherwise, the terms "mounted,"
"connected," "supported," and "coupled" and variations thereof are
used broadly and encompass both direct and indirect mountings,
connections, supports, and couplings.
[0032] In addition, it should be understood that embodiments may
include hardware, software, and electronic components or modules
that, for purposes of discussion, may be illustrated and described
as if the majority of the components were implemented solely in
hardware. However, one of ordinary skill in the art, and based on a
reading of this detailed description, would recognize that, in at
least one embodiment, the electronic-based aspects may be
implemented in software (e.g., stored on non-transitory
computer-readable medium) executable by one or more processing
units, such as a microprocessor and/or application specific
integrated circuits ("ASICs"). As such, it should be noted that a
plurality of hardware and software based devices, as well as a
plurality of different structural components, may be utilized to
implement the embodiments. For example, "servers" and "computing
devices" described in the specification can include one or more
processing units, one or more computer-readable medium modules, one
or more input/output interfaces, and various connections (e.g., a
system bus) connecting the components.
[0033] Other aspects of the embodiments will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 illustrates a lighting system for controlling one or
more LED lighting fixtures.
[0035] FIG. 2 is a block diagram of a lighting control system for
the lighting fixture of FIG. 1.
[0036] FIG. 3 is a perspective view of a lighting fixture with a
LED light source.
[0037] FIG. 4 is a graph of the CIE 1931 color space illustrating
reference chromaticities and a target chromaticity.
[0038] FIG. 5 is a graph of spectral power distributions for the
reference chromaticities of FIG. 4.
[0039] FIG. 6 illustrates distances between reference
chromaticities and a target chromaticity in a generalized color
space.
[0040] FIG. 7 is a flow diagram of a method for determining a
target spectral power distribution.
[0041] FIG. 8 is a graph of two reference spectral power
distributions and an interpolated spectral power distribution based
on the two reference spectral power distributions.
[0042] FIG. 9 is a flow diagram of a method for determining a
target spectral power distribution.
[0043] FIG. 10 is a graph of two reference spectral power
distributions and a multiplicative spectral power distribution
based on the two reference spectral power distributions.
[0044] FIG. 11 is a graph of the CIE 1931 color space illustrating
a chromaticity and various transparency variants thereof.
[0045] FIG. 12 is a graph of spectral power distributions of the
chromaticity and various transparency variants of FIG. 11.
[0046] FIG. 13 is a flow diagram of a method for determining a
target spectral power distribution.
DETAILED DESCRIPTION
[0047] FIG. 1 illustrates a lighting system 100 for controlling a
plurality of LED light fixtures. The system 100 includes a
plurality of user input devices 105-120, a control board or control
panel 125, a first light fixture 130, a second light fixture 135, a
third light fixture 140, a fourth light fixture 145, a database
150, a network 155, and a server-side mainframe computer or server
160. The plurality of user input devices 105-120 include, for
example, a personal or desktop computer 105, a laptop computer 110,
a tablet computer 115, and a mobile phone (e.g., a smart phone)
120.
[0048] Each of the devices 105-120 is configured to communicatively
connect to the server 160 through the network 155 and provide
information to, or receive information from, the server 160 related
to the control or operation of the system 100. Each of the devices
105-120 is also configured to communicatively connect to the
control board 125 to provide information to, or receive information
from, the control board 125. The connections between the user input
devices 105-120 and the control board 125 or network 155 are, for
example, wired connections, wireless connections, or a combination
of wireless and wired connections. Similarly, the connections
between the server 160 and the network 155 or the control board 125
and the light fixtures 130-145 are wired connections, wireless
connections, or a combination of wireless and wired
connections.
[0049] The network 155 is, for example, a wide area network ("WAN")
(e.g., a TCP/IP based network), a local area network ("LAN"), a
neighborhood area network ("NAN"), a home area network ("HAN"), or
personal area network ("PAN") employing any of a variety of
communications protocols, such as Wi-Fi, Bluetooth, ZigBee, etc. In
some implementations, the network 155 is a cellular network, such
as, for example, a Global System for Mobile Communications ("GSM")
network, a General Packet Radio Service ("GPRS") network, a Code
Division Multiple Access ("CDMA") network, an Evolution-Data
Optimized ("EV-DO") network, an Enhanced Data Rates for GSM
Evolution ("EDGE") network, a 3 GSM network, a 4 GSM network, a 4G
LTE network, a 5G New Radio, a Digital Enhanced Cordless
Telecommunications ("DECT") network, a Digital AMPS ("IS-136/TDMA")
network, or an Integrated Digital Enhanced Network ("iDEN")
network, etc. In some embodiments, the network 155 is internal and
local to the server 160. For example, an integrated system with a
database, storage, keyboard, controllers may be provided. In some
embodiments, network connections to the light fixtures 130-145 may
be formed with DMX-512 networks.
[0050] FIG. 2 illustrates a controller 200 for the system 100. The
controller 200 is electrically and/or communicatively connected to
a variety of modules or components of the system 100. For example,
the illustrated controller 200 is connected to one or more
indicators 205 (e.g., LEDs, a liquid crystal display ["LCD"],
etc.), a user input or user interface 210 (e.g., a user interface
of the user input device 105-120 in FIG. 1), and a communications
interface 215. The controller 200 is also connected to the control
board 125. The communications interface 215 is connected to the
network 155 to enable the controller 200 to communicate with the
server 160. The controller 200 includes combinations of hardware
and software that are operable to, among other things, control the
operation of the system 100, control the operation of the light
fixtures 130-145, communicate over the network 155, communicate
with the control board 125, receive input from a user via the user
interface 210, provide information to a user via the indicators
205, etc.
[0051] In the embodiment illustrated in FIG. 2, the controller 200
would be associated with one of the user input devices 105-120. As
a result, the controller 200 is illustrated in FIG. 2 is being
connected to the control board 125 which is, in turn, connected to
the first light fixture 130, the second light fixture 135, the
third light fixture 140, and the fourth light fixture 145. In other
embodiments, the controller 200 is included within the control
board 125, and, for example, the controller 200 can provide control
signals directly to the first light fixture 130, the second light
fixture 135, the third light fixture 140, and the fourth light
fixture 145. In some embodiments, the controller 200 is associated
with (e.g., included within) a light fixture 130-145. In other
embodiments, the controller 200 is associated with the server 160
and communicates through the network 155 to provide control signals
to the control board 125 and the first light fixture 130, the
second light fixture 135, the third light fixture 140, and the
fourth light fixture 145. Spectral power distributions known in the
industry or created by a user can be stored on the server 160 and
accessed from the server 160.
[0052] The controller 200 includes a plurality of electrical and
electronic components that provide power, operational control, and
protection to the components and modules within the controller 200
and/or the system 100. For example, the controller 200 includes,
among other things, a processing unit 220 (e.g., a microprocessor,
a microcontroller, or another suitable programmable device), a
memory 225, input units 230, and output units 235. The processing
unit 220 includes, among other things, a control unit 240, an
arithmetic logic unit ("ALU") 245, and a plurality of registers 250
(shown as a group of registers in FIG. 2), and is implemented using
a known computer architecture (e.g., a modified Harvard
architecture, a von Neumann architecture, etc.). The processing
unit 220, the memory 225, the input units 230, and the output units
235, as well as the various modules or circuits connected to the
controller 200 are connected by one or more control and/or data
buses (e.g., common bus 255). The control and/or data buses are
shown generally in FIG. 2 for illustrative purposes. The use of one
or more control and/or data buses for the interconnection between
and communication among the various modules, circuits, and
components would be known to a person skilled in the art in view of
the embodiments described herein.
[0053] The memory 225 is a non-transitory computer readable medium
and includes, for example, a program storage area and a data
storage area. The program storage area and the data storage area
can include combinations of different types of memory, such as a
ROM, a RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, a hard
disk, an SD card, or other suitable magnetic, optical, physical, or
electronic memory devices. The processing unit 220 is connected to
the memory 225 and executes software instructions that are capable
of being stored in a RAM of the memory 225 (e.g., during
execution), a ROM of the memory 225 (e.g., on a generally permanent
basis), or another non-transitory computer readable medium such as
another memory or a disc. Software included in the implementation
of the system 100 and controller 200 can be stored in the memory
225 of the controller 200. The software includes, for example,
firmware, one or more applications, program data, filters, rules,
one or more program modules, and other executable instructions. The
controller 200 is configured to retrieve from the memory 225 and
execute, among other things, instructions related to the control
processes and methods described herein. Spectral power
distributions known in the industry or created by a user can be
stored in the memory 225 and accessed from the memory 225. In other
embodiments, the controller 200 includes additional, fewer, or
different components.
[0054] The user interface 210 is included to provide user control
of the system 100 and/or light fixtures 130-145. The user interface
210 is operably coupled to the controller 200 to control, for
example, drive signals provided to the light fixtures 130-145, and
generate and provide control signals to corresponding driver
circuits. The user interface 210 can include any combination of
digital and analog input devices required to achieve a desired
level of control for the system 100. For example, the user
interface 210 can include a computer having a display and input
devices, a touch-screen display, a plurality of knobs, dials,
switches, buttons, faders, or the like. In the embodiment
illustrated in FIG. 2, the user interface 210 is separate from the
control board 125. In other embodiments, the user interface 210 is
included in the control board 125. In some embodiment, the user
interface 210 is separated from the control system 100 (e.g., as a
portable device wirelessly communicatively connected to the
controller 200).
[0055] The controller 200 is configured to work in combination with
the control board 125 to provide direct drive signals to the light
fixtures 130-145. As described above, in some embodiments, the
controller 200 is configured to provide direct drive signals to the
light fixtures 130-145 without separately interacting with the
control board 125 (e.g., the control board 125 includes the
controller 200). The direct drive signals that are provided to the
light fixtures 130-145 are provided, for example, based on a user
input received by the controller 200 from the user interface
210.
[0056] As illustrated in FIG. 2, the controller 200 is connected to
light fixtures 130-145. In some embodiments, each light fixture
130-145 includes a chip-on-board ("COB") light source. A four light
fixture embodiment is illustrated for exemplary purposes only. In
other embodiments, five or more light fixtures are used to further
enhance the system 100's ability to produce visible light.
Conversely, in other implementations, fewer than four light
fixtures are used (i.e., one or two light modules). In some
embodiments, the light fixtures 130-145 are light emitting diode
("LED") light fixtures.
[0057] FIG. 3 illustrates a lighting fixture 260 (i.e., a
luminaire) that can be used, for example, in entertainment
lighting, architectural lighting, etc. The lighting fixture 260
includes a light source 265 that produces light, a mixing assembly
270 that mixes the light, a gate assembly 275 through which the
light passes after exiting the mixing assembly 270, and a lens
assembly 280 that receives the light from the gate assembly 275 and
projects it toward the target or desired location. The light source
265 includes an LED assembly that is configured to produce light in
multiple wave lengths. The LED assembly includes a substrate in the
form of a printed circuit board supporting a plurality of the LEDs.
The plurality of LEDs may, for example, be arranged in an array
(e.g., an LED array). In some embodiments, the LED array is
hexagonal. It should be understood that the precise type, number,
and positioning of the LEDs can be modified substantially without
departing from the teachings disclosed herein. For purposes of
description herein, the lighting fixture 260 could be any one of
the light fixtures 130-145.
[0058] With reference to FIG. 4, the CIE 1931 color space 300 is
illustrated with the Planckian locus 304 shown. In addition, a
plurality of chromaticities 308 are illustrated within the color
space 300. In some embodiments, each of the plurality of
chromaticities 308 correspond to conventional filters that could be
used with incandescent lamps. Any number of the chromaticities 308
are selected as reference chromaticities 312. In the illustrated
embodiment, there are six reference chromaticities 312. For each of
the reference chromaticities 312, there is a corresponding spectral
power distribution 316 (see, e.g., FIG. 5). For example, the
reference chromaticities 312 include a first chromaticity 312A with
a first spectral power distribution 316A, a second chromaticity
312B with a second spectral power distribution 316B, a third
chromaticity 312C with a third spectral power distribution 316C, a
fourth chromaticity 312D with a fourth spectral power distribution
316D, a fifth chromaticity 312E with a fifth spectral power
distribution 316E, and a sixth chromaticity 312F with sixth
spectral power distribution 316F. The reference chromaticities 312
and their corresponding spectral power distributions 316 may be
stored in the memory 225 of the controller 200. A target or desired
chromaticity 320 (i.e., a target color) is also illustrated in the
color space 300. In the illustrated embodiment, the reference
chromaticities 312 are the six closest colors to the desired
chromaticity 320 in the x-y CIE 1931 color space 300. In some
embodiments the desired chromaticity 320 is selected by a user. In
other embodiments, the desired chromaticity 320 is automatically
selected by the processing unit 220 based on user preferences or
settings.
[0059] With the desired chromaticity 320 indicated or selected, a
corresponding desired output spectral power distribution based on
the reference chromaticities 308 and their corresponding spectral
power distributions 316 is determined or calculated. The desired
output spectral power distribution for the desired chromaticity 320
is determined based on at least one reference spectral power
distribution 316. Several embodiments for determining the desired
output spectral power distribution based on at least one reference
spectral power distribution are disclosed herein.
[0060] A first method to determine the desired output spectral
power distribution based on at least one reference spectral power
distribution is an interpolative method. Let {.sub.n} be a set of
known spectral power distributions at determined chromaticities
312. See, for example, the reference chromaticities 312 with
reference spectral power distributions S.sub.1, S.sub.2, S.sub.3 .
. . S.sub.n in FIG. 6. For a user-selected target chromaticity 320,
the corresponding desired spectral power distribution is determined
by EQN. 1:
=.SIGMA..sub.i=1.sup.nf(d.sub.i,p.sub.i)*.sub.i EQN. 1
where d.sub.i represents a chromaticity distance, p.sub.i
represents a generalized preference parameter determined
heuristically or through explicit user interaction, and where f
represents a generalized weighting function (e.g., polynomial,
power, logarithmic, exponential, etc.). In some embodiments, the
generalized preference parameter is based on a user preference.
Specifically, the user preference may be a desired amount of a
particular waveband (e.g., color channel) in the output spectral
power distribution.
[0061] With reference to FIG. 6, the chromaticity distance d.sub.i
(i.e., d.sub.1, d.sub.2, d.sub.3 . . . d.sub.n) is representative
of how far away the reference chromaticities 312 are from the
target chromaticity 320. The chromaticity distance, d.sub.1, can be
computed using one or more of the following values:
MacAdam-ellipses in the CIE 1931 x-y color space; Euclidean
distance in the CIE 1960 u-v color space; .DELTA.E* in the L*a*b*
color space; the Manhattan distance in a discretized color space
(i.e., the taxicab distance, the sum of the absolute difference of
the cartesian coordinates); or some other uniquely-determined
distance in a color space. In some embodiments, the first distance
is measured between MacAdam ellipses corresponding to the desired
chromaticity and the first chromaticity in the CIE 1931 x-y color
space. In other embodiments, the first distance is the Euclidean
distance between the desired chromaticity and the first
chromaticity in the CIE 1960 u-v color space. In other embodiments,
the first distance is the delta E (.DELTA.E*) between the desired
chromaticity and the first chromaticity in the CIE L*a*b* color
space. In other embodiments, the first distance is the sum of the
absolute difference of the cartesian coordinates of the desired
chromaticity and the first chromaticity.
[0062] The weighting function, f, is configured to ensure or
prioritize one or more of the following: continuity in the target
spectrum at different chromaticities; consistency between the
target spectrum and various elements of known spectral power
distributions at determined chromaticities; or algorithm
performance in a particular luminaire.
[0063] The known spectral power distributions {.sub.n} used in the
interpolative method can be various subsets of reference
chromaticities 308. For example, in some embodiments, {.sub.n} is a
subset (proper or improper) of a family or families of conventional
filters, known to those practiced in the art, and with a
user-configurable illuminant, including, but not limited to, CIE
standard illuminants. In other embodiments, {.sub.n} is a subset
(proper or improper) of a family or families of prior user-created
spectral power distributions, stored by the user in the memory 225
in advance and recalled for the present calculation. In still other
embodiments, {.sub.n} is a subset (proper or improper) of a family
or families of physical emission spectra (e.g., thermal blackbody
emission, biological phosphorescence, or spectra of various
chemical elements or compounds). As a result, the known spectral
power distributions from which to interpolate the target spectral
power distribution can be the spectral power distributions from
filters, tungsten lamps, black body emitters, etc.
[0064] FIG. 7 is a method 400 for controlling and operating the
lighting fixtures 130-145 at the desired chromaticity 320 with the
desired output spectral power distribution, . The method 400
includes determining a first distance, d.sub.1, between the desired
chromaticity 320 and a first chromaticity 312A with a first
spectral power distribution S.sub.1 (STEP 404). The method 400 also
includes determining a second distance, d.sub.2, between the
desired chromaticity 320 and a second chromaticity 312B with a
second spectral power distribution S.sub.2 (STEP 408). STEP 412
includes scaling the first spectral power distribution S.sub.1 by a
first scaling factor to arrive at a first scaled spectral power
distribution. The first scaling factor is based on the first
distance d.sub.1. Likewise, STEP 416 includes scaling the second
spectral power distribution S.sub.2 by a second scaling factor to
arrive at a second scaled spectral power distribution. The second
scaling factor is based on the second distance d.sub.2. In the
illustrated embodiments, the scaling at STEP 412 and STEP 416 is
performed according to EQN. 1. As such, the first and second
scaling factors are determined by the weighting function, f, of
EQN. 1. At STEP 420, the first scaled spectral power distribution
and the second scaled spectral power distribution are added
together (i.e., summed) to arrive at a summed spectral power
distribution. Next, STEP 422 includes using the summed spectral
power distribution and the desired chromaticity 320 to generate a
target output spectral power distribution 324. In some embodiments,
STEP 422 can include calculating a spectral power distribution
using conventional methods, such as those described in U.S. Pat.
No. 8,723,450, the entire content of which is incorporated herein.
In other words, using EQN. 1 and reference spectral power
distributions, the target output spectral power distribution is
determined. For example, with reference to FIG. 8, the target
output spectral power distribution 324 is determined from reference
spectral power distributions S.sub.1 and S.sub.2. Next, STEP 424
includes driving the plurality of light sources (i.e., the
plurality of LEDs) within the lighting fixtures 130-145 at power
intensities that correspond to the desired output spectral power
distribution.
[0065] A second method to determine the desired output spectral
power distribution based on at least one reference spectral power
distribution is a multiplicative method. Let {.sub.n} be a
user-selected set of known spectral transmissivities, for example,
theatrical filters, and let be a user-configurable illuminant. The
corresponding target spectral power distribution is determined by
EQN. 2:
=*.PI..sub.i=1.sup.n.sub.i EQN. 2
[0066] The multiplicative method is operable to simulate the
physical stacking (i.e., "sandwich") of a plurality of physical
filters. Filter stacking or a filter sandwich was traditionally
used to achieve a desired affect by combining more than one
physical filter in series at the output of a lighting fixture. The
multiplicative method can produce a discrete set of chromaticities
(since {.sub.n} is finite). In some embodiments, the multiplication
is on a by-wavelength basis. Practically, the number of subsets of
{.sub.n} is extremely large, so the limiting factor becomes the
discretization and addressable color space of the luminaire. In
some embodiments, a user may select a target chromaticity and at
least one known spectral transmissivity and illuminant , and
compute a minimally-different spectral target .
[0067] FIG. 9 is a method 500 for controlling and operating the
lighting fixtures 130-145 at the desired chromaticity with the
desired output spectral power distribution. The method 500 includes
multiplying a first spectral power distribution 516A (see FIG. 10)
by a second spectral power distribution 516B (see FIG. 10) to
arrive at a product spectral power distribution (STEP 504). In some
embodiments, the product spectral power distribution corresponds to
the spectral power distribution resulting from a combination of at
least two physical filters (e.g., two gel filters). The method 500
also includes multiplying the product spectral power distribution
by an illuminant spectral power distribution, I, to arrive at the
desired output spectral power distribution 528 at the desired
chromaticity (STEP 508). In some embodiments, the illuminant
spectral power distribution corresponds to the spectral power
distribution of a tungsten lamp. In some embodiments, STEP 504 and
STEP 508 are reversed or combined into a single step, corresponding
to EQN. 2. Next, at STEP 512, the plurality of light sources (i.e.,
the plurality of LEDs) within the lighting fixtures 130-145 are
driven at intensities that correspond to the desired output
spectral power distribution 528.
[0068] A third method to determine the desired output spectral
power distribution based on at least one reference spectral power
distribution is a logarithmic or exponential method. Let S be a
user-selected spectral transmissivity, such as a theatrical filter.
For a user-selected opacity (or alternatively, optical depth) .tau.
and user-configurable illuminant , the corresponding target
spectral power distribution is determined by EQN. 3:
=*.sup..tau. EQN. 3
The third method is configured to simulate various thicknesses
(i.e., transparency) of a physical filter. The multiplication and
exponentiation are understood to be on a by-wavelength basis.
Although a negative opacity is not achievable with a physical
filter, such spectral solutions are possible utilizing the third
method and EQN. 3. For example, EQN. 3 may determine an output
spectral power distribution for a negative opacity. For a
user-selected chromaticity, the closest point on the chromaticity
locus is traced out by varying the opacity r and this value is used
to compute the target spectrum as above. See, for example, FIG. 11
that illustrates a reference chromaticity 614A and the
corresponding transparency or opacity variant chromaticities
620A-620D. In the illustrated embodiment, chromaticity 620A
corresponds to a 1/2 opacity of the chromaticity 614A and
chromaticity 620B corresponds to a 1/4 opacity of the chromaticity
614A. Likewise, chromaticity 620C corresponds to a zero opacity of
the chromaticity 614A (i.e., the chromaticity 620C is located on
the Planckian locus 304). In addition, chromaticity 620D
corresponds mathematically to a negative 1/4 opacity of the
chromaticity 614A. The corresponding spectral power distributions
are illustrated in FIG. 12. Specifically, the reference spectral
power distribution 616A corresponds to the reference chromaticity
614A and the target spectral power distributions 632A-632D
correspond to the target chromaticities 620A-620D,
respectively.
[0069] FIG. 13 is a method 600 for controlling and operating the
lighting fixtures 130-145 at the desired chromaticity with the
desired output spectral power distribution. The method 600 includes
exponentiating a first spectral power distribution (e.g., 616A) by
an exponent to arrive at an exponential spectral power distribution
(STEP 604). In some embodiments, the exponent corresponds to a
user-selected opacity. Also, in some embodiments, the user-selected
opacity is a negative value. The method 600 also includes
multiplying the exponential spectral power distribution by an
illuminant spectral power distribution, I, to arrive at the desired
output spectral power distribution (e.g., 632A) at the desired
chromaticity (e.g., 620A) (STEP 608). In some embodiments, the
illuminant spectral power distribution corresponds to the spectral
power distribution of a tungsten lamp. In some embodiments, STEP
604 and STEP 608 are combined into a single step, corresponding to
EQN. 3. Next, at STEP 612, the plurality of light sources (i.e.,
the plurality of LEDs) within the lighting fixtures 130-145 are
driven at intensities that correspond to the desired output
spectral power distribution 632A.
[0070] With reference to all three described methods 400, 500, and
600, they provide methods for selecting the spectral content of a
light in a controlled manner to change its rendering performance
and visual perception at a given chromaticity. In some embodiments,
the controller 200 is adaptive and anticipates the user's
preferences as the user selects, computes, and stores cues, states,
or settings throughout the color space. For example, a user may
find themselves boosting the amber emitter in most cues, states, or
settings because of, perhaps, the scene, venue, or desired mood or
atmosphere. By using the existing user cues, states, or settings as
the subset {.sub.n} in, for example EQN. 1, new cues, states, or
settings can be generated at different chromaticities that would
automatically contain a similar amber boost.
[0071] Various features and advantages are set forth in the
following claims.
* * * * *